| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel for machine structural use which is excellent in the wear resistance of cemented carbide tools and in the chip treatability, solves the problems of showing no free cutting property in machining works and of deteriorating the material quality, improves the chip treatability in deep drilling works and also has an excellent machinability in a wide range of cuttings without a serious reduction in the strength. SOLUTION: The steel comprises, on the basis of mass%, 0.39-0.65% C, 0.03-1.00% Si, 0.30-2.50% Mn, 0.03-0.35% S, 0.005-0.060% Al, 0.0005-0.020% Ca, 0.0005-0.020% Mg and the balance being Fe and unavoidable impurities. The steel contains as sulfide-based inclusions one or more kinds of Mns, CaS, MgS, (Ca, Mn)S and (Mg, Mn)S, and moreover one or two kinds of (Ca, Mg)S and (Ca, Mg, Mn)S and has small anisotropy of mechanical properties and excellent machinabilty for a large, stable drilling depth. COPYRIGHT: (C)2004,JPO
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